U.S. patent number 8,806,813 [Application Number 11/848,766] was granted by the patent office on 2014-08-19 for technique for electrically bonding solar modules and mounting assemblies.
This patent grant is currently assigned to PVT Solar, Inc.. The grantee listed for this patent is Joshua Reed Plaisted, Brian West. Invention is credited to Joshua Reed Plaisted, Brian West.
United States Patent |
8,806,813 |
Plaisted , et al. |
August 19, 2014 |
Technique for electrically bonding solar modules and mounting
assemblies
Abstract
A mounting system is provided for an array of solar modules. The
mounting system includes one or more rail assemblies that extend
lengthwise in a first direction to support a plurality of solar
modules that comprise the array. Each of the one or more rail
assemblies may be configured to compress in order to retain an edge
section of one or more of the plurality of solar modules in an
operable position. A conductive element may be positioned to bond
the edge section of at least one of the plurality of solar modules
with at least a section of the rail assembly that retains that edge
section in the operable position, so as to form a conductive path
for electrical current.
Inventors: |
Plaisted; Joshua Reed (Oakland,
CA), West; Brian (San Francisco, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Plaisted; Joshua Reed
West; Brian |
Oakland
San Francisco |
CA
CA |
US
US |
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Assignee: |
PVT Solar, Inc. (Berkeley,
CA)
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Family
ID: |
39136960 |
Appl.
No.: |
11/848,766 |
Filed: |
August 31, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080053517 A1 |
Mar 6, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60824260 |
Aug 31, 2006 |
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Current U.S.
Class: |
52/173.3;
136/244; 136/251 |
Current CPC
Class: |
F24S
25/35 (20180501); H01R 4/66 (20130101); F24S
25/20 (20180501); F24S 25/636 (20180501); H02S
20/23 (20141201); H01R 4/64 (20130101); F24S
2025/6004 (20180501); H01R 4/26 (20130101); Y02E
10/50 (20130101); Y02B 10/10 (20130101); Y02E
10/47 (20130101); Y02B 10/12 (20130101) |
Current International
Class: |
H01L
31/05 (20140101); H01L 31/048 (20140101) |
Field of
Search: |
;52/173.3 ;136/244,251
;439/927 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0614058 |
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EP |
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0905795 |
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Mar 1999 |
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EP |
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1873843 |
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Jan 2007 |
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EP |
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09-184209 |
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Jul 1997 |
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JP |
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10-159201 |
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JP |
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JP |
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2004-251037 |
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JP |
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WO 02/41407 |
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May 2002 |
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WO |
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Other References
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cited by applicant .
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Primary Examiner: Canfield; Robert
Attorney, Agent or Firm: Armstrong Teasdale LLP
Parent Case Text
RELATED APPLICATIONS
This application claims benefit of priority to Provisional U.S.
Patent Application No. 60/824,260, filed Aug. 31, 2006, and
entitled METHODS FOR GROUNDING SOLAR MODULES AND MOUNTING SYSTEMS.
The aforementioned priority application is hereby incorporated by
reference.
Claims
What is claimed is:
1. A rail assembly for a mounting system that supports an array of
solar modules, the rail assembly comprising: a top section; a
bottom section that is combinable with the top section to extend
lengthwise in a first direction, a portion of the top rail section
being compressed into the bottom rail section; wherein at least one
of the top section and the bottom section are structured so that a
receiving structure is provided for horizontally receiving an edge
section of a frame of a solar module in an operative position; a
compression mechanism that is usable to create a compression force
that compresses the top section and the bottom section into
retaining and supporting the edge section of the frame of the solar
modules in an operable position within the receiving structure; and
a conductive element extending along one of the top section and
bottom section, the conductive element including a segment that is
provided between the top section and bottom section, the segment
including one or more pointed protrusions that extend and make
contact with at least one of the top section and bottom section,
wherein the one or more protrusions are positioned to be effected
by the compression force of the compression mechanism in forming an
electrical bond with the edge section of the frame of the solar
module and enabling a conductive path for electrical current.
2. The rail assembly of claim 1, wherein the conductive element
includes at least a thickness that extends between a surface of the
receiving structure and the frame of the solar module, and wherein
the thickness of the conductive element on the receiving structure
is shaped to include a peak and a trough.
3. The rail assembly of claim 1, wherein the surface of the
receiving structure corresponds to a ledge, and wherein the
conductive element is unitarily formed with at least a portion of
the ledge.
4. The assembly of claim 1 wherein the segment comprises conductive
studs, and wherein the segment is provided on a separate polymer
strip.
5. The rail assembly of claim 1, wherein the compression force of
the compression member actively bonds the one or more protrusions
to at least one of the solar modules.
Description
TECHNICAL FIELD
The disclosed embodiments relate generally to the field of solar
modules and mounting systems. In particular, the disclosed
embodiments relate to mechanisms for electrically bonding or
grounding solar modules and mounting systems for solar modules.
BACKGROUND
Current methods of installing proper bonding devices for
PhotoVoltaic (PV) modules and other types of solar modules is both
expensive and time consuming. Most electrical codes require a
grounding wire to be mechanically bonded to each PV module frame
within an array of PV modules as well as to the overall mounting
system itself.
There are two prevalent bonding methods that represent the state of
the art. One uses an assembly of a screw and a custom washer to
attach the grounding wire to the PV module such as illustrated in
the installation manuals from many PV module manufacturers. Though
a simple solution, it is time consuming to bond modules in this
manner due to the need to wrap the grounding wire around each
screw. Also, since the parts involved with this method are small
and discrete, they are hard to handle and assemble on a rooftop
during typical installations.
Another typical attachment method is to use a relatively expensive
bonding lug such as those manufactured by Ilsco of Cincinnati Ohio.
Although use of a bonding lug does not necessitate wrapping the
grounding wire, the installation is also labor intensive and
awkward because of its two-step process: first the lug has to be
fastened to the frame of the PV module and then the wire must be
clamped into the lug using a second fastener such as a set
screw.
BRIEF DESCRIPTION
FIG. 1A illustrates a rail assembly for use as part of a larger
solar module mounting assembly, according to an embodiment of the
invention.
FIG. 1B is a close-up of a portion of the conductive element of
FIG. 1A, under an embodiment of the invention.
FIG. 2A illustrates a bonding clip for use as a conductive element,
in accordance with an embodiment of the invention.
FIG. 2B is a frontal view of clip of FIG. 2A, along lines A-A,
under an embodiment of the invention.
FIG. 2C illustrates an embodiment in which an alternative clip is
provided, according to an embodiment of the invention.
FIG. 3 is an exploded side view of a rail assembly configured to
include one or more bonding features, under another embodiment of
the invention.
FIG. 4 illustrates another rail assembly configuration for
promoting electrical bonding in a mounting system, under an
embodiment of the invention.
FIG. 5 illustrates another rail assembly configuration for
promoting electrical bonding in a mounting system, under an
embodiment of the invention.
FIG. 6 is an exploded view of a mounting assembly that includes a
strut runner, under an embodiment of the invention.
FIG. 7 illustrates a mounting assembly, under an embodiment of the
invention.
DETAILED DESCRIPTION
Embodiments described herein enable use of conductive elements on
mounting assemblies for solar modules, for purpose of creating
bonding or grounding points. As described, embodiments provide that
such conductive elements are included between the engagement of the
solar modules and the rail assemblies or support structures that
hold the solar modules in place. Conductive paths for bonding or
grounding purposes may then be formed that require minimal
additional steps in assembling the mounting assembly as a whole.
One or more embodiments enable such bonding or grounding features
to be incorporated into the solar module array with assembly steps
that eliminate the need for running grounding/bonding elements as
separate assembly requirements.
According to an embodiment, a mounting system is provided for an
array of solar modules. The mounting system includes one or more
rail assemblies that extend lengthwise in a first direction to
support a plurality of solar modules that comprise the array. Each
of the one or more rail assemblies may be configured to compress in
order to retain an edge section of one or more of the plurality of
solar modules in an operable position. A conductive element may be
positioned to bond the edge section of at least one of the
plurality of solar modules with at least a section of the rail
assembly that retains that edge section in the operable position,
so as to form a conductive path for electrical current. The
conductive paths may extend from the edge section to at least the
one or more rail assemblies.
Although numerous embodiments described herein are described in the
context of a particular style of a Common Compressed Rail (CCR)
mounting system, embodiments described herein may be implemented
with other structures and mounting systems. In particular,
embodiments described herein apply across an entire range of
similar mounting systems. A particular benefit of combining
embodiments such as described herein with CCR systems is that the
upper and lower mounting rails may share a common edge with the
solar module frames. Therefore, if bonding features of any kind are
provided at regular intervals, it will be guaranteed that the solar
module frame and mounting rail will be mating surfaces.
FIG. 1A illustrates a rail assembly for use as part of a larger
solar module mounting assembly, according to an embodiment of the
invention. As will be described, conductive elements may be
included or used with a rail assembly 100 to enable the passage of
electrical current between one or more solar module frames and the
mounting system. Enabling the passage of electrical currents in a
manner provided for by embodiments described herein enables a
mounting assembly or system to handle, for example, electrical
shorts on individual solar modules, lightening strikes, or other
events which can be dangerous or harmful to equipment.
With reference to embodiments described herein, a mounting assembly
generally includes solar modules, rail assemblies, and strut
runners. The solar modules include a combination of a solar panel
and a frame that holds the solar panel. The panel itself may
include solar cells or other solar-sensitive material such as a
thermal absorber. The rail assemblies provide a primary support for
retaining solar modules in position. U.S. patent application Ser.
Nos. 10/855,254 11/332,000 (both of which are hereby incorporated
by reference in their respective entirety) for example, illustrate
the use and context of a rail assembly for use in retaining and
supporting solar modules in operable positions to receive sunlight.
Generally, the strut runners interconnect the rail assemblies and
provide support for the rail assemblies by securing the rail
assemblies to an underlying structure (such as a roof top).
According to an embodiment, the rail assembly 100 is structured to
retain a solar module in an operable position (i.e. directed to
receive sunlight). The solar module 101 includes a frame 104 and a
panel 109 having solar sensitive materials. The rail assembly 100
includes a top rail section 105 and a bottom rail section 106 that
combine to form a receiving structure 122. In order to support the
solar module 101, the top and bottom rail sections 105, 106 are
compressed while an edge section 126 of the frame 104 of the solar
module 101 is inserted or retained with the receiving structure
122. The receiving structure 122 may include a ledge surface 124,
which in an embodiment shown is provided by the bottom rail section
106. Absent intermediate structures described herein, the top rails
section 105 is compressed into the bottom rail section 106 to
tighten a dimension of the receiving structure 122, and cause the
receiving structure 122 to grip the frame 104 against the ledge
surface 124.
A conductive element 102 is positioned between the frame 104 and
the rail assembly 100. In one embodiment, the conductive element
102 is sandwiched between the frame and the ledge surface 124,
where the active compression force for compressing the top and
bottom rail structures 105, 106 is in effect. In an embodiment, the
conductive element 102 is provided as a thickness over the ledge
surface 124 (to be between the frame 104 and the ledge surface
124). In one embodiment, the conductive element 102 is a clip
extending on an underside of the frame 104. The clip formation of
conductive element 102 may enable it to grip with bias an edge 114
of the frame 104. A strip 115 may extend underneath the frame 104,
so as to be positioned over the ledge surface 124. A protrusion 135
may be positioned on the strip 115 so as to be in contact with the
ledge surface 124 when the top and bottom rail sections 105, 106
are under compression.
To provide compression, one or more embodiments provide for a
compression bolt 130 that interconnects (with compression) the top
and bottom rail sections 105, 106. A structure 132 may receive the
bolt 130. Under one implementation, the receiving structure 132 is
in the form of a captive nut formed from metal such as steel. A
washer 133 may be used under the bolt 130 to spread the compressive
force. The washer 133 may be serrated to promote electrical bonding
between the bolt 130 and the top rail structure 105. The receiving
structure 132 may take several forms, including the form of a
threaded insert. Alternatively, structure 132 may be formed
directly on the bottom rail structure 106 through a drilling and
tapping process such that it is electrically bonded to the lower
mounting rail 106.
When tightened, compression is applied through bolt 130 and
receiving structure 132. The compression may act to reduce a
dimension of the receiving structure 122, thereby forcing the frame
104 against the ledge surface 124. The conductive element 102 is
compressed between the frame 104 and the ledge surface 124, with
the protrusion 135 being bonded with the ledge surface 124.
A resulting conductive path is provided from the frame 104 to the
rail assembly 100 to enable passage of electrical current for
bonding the frame to the rail assembly. As will be described, the
rail assembly 100 may be interconnected to other components to
enable grounding of the elements within the solar array.
FIG. 1B illustrates that the thickness of the conductive element
may have varying dimensions when provided on the ledge surface 124.
According to an embodiment, the thickness, shown in the form of
protrusion 135, includes a peak 134 and a trough 136 (thus defining
one or more peaks). One embodiment provides that at minimum, the
peak 134 and trough 136 may be visually distinguishable, so as to
be vertically separated by a distance that is greater than 1
mm.
FIG. 2A illustrates a bonding clip 210 for use as a conductive
element, in accordance with an embodiment of the invention. The
bonding clip 210 may include multiple bonding features 205 designed
to enable or enhance electrical contact between an underside of the
frame 104 (FIG. 1A) and the ledge surface 124 (FIG. 1A). In an
embodiment, the clip 210 includes a first panel 212 that is joined
with a second panel 214 via a radius bend 216. A gap 218 is defined
in the structure for gripping the edge of the frame 104. The radius
bend 216 enables the panels 212, 214 to be biasely separated, so as
to increase a dimension of the gap 218. The dimension of the gap
218 may be designed so that when the clip 210 is in an unbiased
state, the gap 218 is less than a dimension of the thickness of the
edge 114. The clip 210 can be biasely enlarged to positively grip
the edge 114 of frame 104 and remain in position.
To provide a secure electrical bond with the frame 104 (FIG. 1A),
bonding features 205 may be in the form of teeth or protrusions
that grip into one of the surfaces of the frame. The bonding
features 205 may be provided on one or both inner surfaces 207, 209
provided by panels 212, 214. One of the exterior surfaces 211 may
also include bonding features 215 (shown in FIG. 2B) to bond with
the ledge surface 124 of the receiving structure 122.
FIG. 2B is a frontal view of clip 210, along lines A-A, under an
embodiment of the invention. As shown, bonding features 205 may be
provided on an interior surface 207 that partially defines gap 218
along with interior surface 209. The panels 212, 214 may biasely
separate to increase dimension of gap 218, enabling the edge 114 of
frame 104 to be inserted therein. A lower bonding feature 215 is
extended from clip 210. In an embodiment such as shown by FIG. 1A,
the lower bonding features 215 bonds to the ledge surface 124.
Under one embodiment, the lower bonding features 215 is also
sharpened to tooth-shaped to enhance the bond under compression.
Sharpened features such as shown by bonding features 205, 215 also
provide added benefit of penetrating through any coated surface
that may be provided on either the frame 104 or ledge surface 124,
including paint, anodization, or corrosion.
In FIGS. 2A and 2B, bonding features 205, 215 may be formed during
the die stamping process used to fabricate the clip 210. Other
implementations of the protrusions are also possible and may range
from raised and pointed cones to the sharp open barbs found on fine
grating devices. Alternately, the bonding features 205, 215 may be
formed such that an enclosed contact area is formed to specifically
exclude introduction of air or moisture that could oxidize the
contact area and inhibit the electrical bond. One purpose of the
bonding features 205, 215 includes penetration of any coatings on
the mating surfaces to provide good and constant electrical contact
between the frame 104 and the rail assembly 100 (or other portion
of a larger mounting assembly). This can be achieved though a
multitude of features and should not be restricted to those
outlined above.
According to an embodiment, clip 210 may serve an additional
purpose of retaining any wiring in the solar array, such as
interconnections between solar PV modules. The use of such a
feature hides the wires from view for a more aesthetically pleasing
array and may prevent the wires from abrading over time due to the
wind brushing the wires against a roof or the mounting system
itself.
FIG. 2C illustrates an embodiment in which an alternative clip 260
is shaped to contain a wire-holding loop 270. The wire-holing loop
may be configured to retain any wiring within the solar array. In
this configuration, the remotely located wire-holding loop 270 is
separated from a main body 262 of the clip 260 by a bridge 264,
which allows any wires to be inserted after the bonding clip 260
has been installed.
While embodiments described herein reference conductive element
102, (FIG. 1A) in the form of one of the clip 210 (FIG. 2A) or clip
260 (FIG. 2C), being provided for ledge surface 124, embodiments
provide for other variations and implementations. Among the
variations, rail assembly 100 may not require a ledge surface 124,
but rather may compress the frame 104 using other features of the
receiving structure 122. Thus, for example, any of the conductive
elements (including clips 210, 26) described above may be provided
for the frame 104 compressing against some other structure of the
top or bottom rail section 105, 106 or receiving structure 122. In
one implementation, the frame 104 may include only vertical flanges
as opposed to edge 114, in which case the conductive element (or
one of the clips 210, 260) may be relocated for intimate contact
during the compression.
As an example, one possible arrangement includes placing
alternative bonding features on radius bend 216 of the clip 210, so
that when the clip is installed on a vertically aligned flange, the
alternative bonding features are forced into contact with a surface
of the bottom rail section 106 (FIG. 1A). Alternately, a clip may
be positioned between the frame 104 and the top rail section 105 to
provide electrical contact.
As mentioned, strut runners may form part of an overall mounting
assembly that interconnects rail assemblies and secures rail
assemblies to a rooftop or other underlying structure. One or more
embodiments provide for use of strut runners to provide grounding
or other forms of electrical bonding, in connection with bonding
features described with other embodiments. The use of strut runners
enables, for example, electrical current caused from a shorted PV
module or a lightening strike to be grounded or carried away from
the mounting structure.
Both the top rail section 105 (FIG. 1A) and bottom rail section 106
(FIG. 1A) may be formed from extruded Aluminum, formed steel, or
other electrically conducting material of sufficient cross section
to act as electrical buss-bars. Such construction enables the
formation of an electrical bond between separate solar modules
arranged along their length. Moreover, the use of bolt 130 to
attain compression of the top and bottom rail sections 105,106 for
each of multiple solar modules 101 in a column may be leveraged.
More specifically, the column arrangement provides for multiple
bolts 130 to also be aligned vertically with the rail sections. The
bolts 130 may provide electrical continuity between the top rail
section 105 and bottom rail section 106, so as to properly bond the
entire mounting system and thus allowing current to freely pass
between all members. This same regular pattern of bolts 130 assures
sufficient pressure upon the solar module frames to compress the
conductive elements 102 (FIG. 1A), which as described with FIG. 2A
and FIG. 2C, may correspond to clips 210 or clips 260.
FIG. 3 is an exploded side view of a rail assembly configured to
include one or more bonding features, under another embodiment of
the invention. In FIG. 3, rail structure 300 may, as described with
an embodiment of FIG. 1A, include a top rail section 305 that
compresses against a bottom rail section 306. The combined rail
sections 305, 306 may form the receiving structure that includes
the ledge surface 324. In one embodiment, the compression mechanism
is provided by the bolt 330, which secures into receiving structure
332. Washer 333 may be used under bolt 330 to spread the
compressive force. When the top and bottom rail sections 305, 306
compress, they retain an edge section 326 of the solar module 301,
so that the solar panel 309 is in an operable position (i.e. to
receive sunlight).
As further described with an embodiment of FIG. 1A, one or more
embodiments provide for use of conductive elements 302 to
electrically bond the frame 304 of the solar module 301 and the
rail assembly 300. In an embodiment of FIG. 3, the conductive
elements 302 are in the form of a strip 310.
FIG. 3 illustrates another rail assembly configuration for
promoting electrical bonding in a mounting system, under an
embodiment of the invention. As described, an embodiment of FIG. 3
provides for use of a bonding strip 310 to electrically bond (and
protect) a mounting assembly. In an embodiment, the bonding strip
310 is a thickness of material that is placed between the solar
module frame 304 and the top and bottom rails structures 305, 306.
In one implementation, the bonding strip 310 may contain multiple
sharp protrusions 302 on both a top and bottom surface 311, 313.
These protrusions 302 may penetrate the surfaces of the solar
module frame 304 and corresponding top or bottom rail sections
305,306. When the rail sections 305,306 are compressed, the sharp
protrusions 302 penetrate any coatings on the solar module frame
304, as well as on the particular top or bottom rail section
305,306 that is contact. The result is the establishment of a
secure electrical bond for the passage of electrical current.
Although the bonding strip 310 is shown placed on both sides of the
solar module frame 304, an alternative embodiment may employ only a
single bonding strip 310. For example, the bonding strip 310 may be
employed on just the bottom rail section 306, or just the top rail
section 305.
The bonding strip 310 may be formed through any one of many
possible processes. One possible process includes using a die punch
or to roll form a metal strip that integrally forms the protrusions
302 in forms analogous to those used in the bonding clip of FIGS.
2A-2C. Alternately, conductive studs could be embedded into a
polymer or rubber strip wherein the studs protrude from both sides
of the bonding strip 310. In such a case, only the studs need to be
conductive and the strip itself is just a carrier that can be made
from conductive or non-conductive materials. Another possible
process is to utilize commercially available contact strips such as
the MULTILAM product series manufactured by MULTI-CONTACT of Santa
Rosa, Calif. among others.
FIG. 4 illustrates another rail assembly configuration for
promoting electrical bonding in a mounting system, under an
embodiment of the invention. As described, an embodiment of FIG. 4
provides for use of discrete bonding pins 410 instead of, for
example, the strip 310. For simplicity, the rail assembly 400 is
shown to have a construction described with an embodiment of FIG.
1A or FIG. 3. According to one embodiment, the bonding pins 410
include conductive points that are fastened to the solar module
frame 404, or alternatively to the top and bottom rail sections
405, 406. When the top and bottom rail sections 405, 406 are
compressed by the bolt 430, the bonding pins 410 penetrate into the
solar module frame 404 and/or top and bottom rail sections 405,
406. In one implementation, the bonding pins 410 are in the form of
barbed or press fitted metal studs that provide intimate electrical
contact. In alternative implementations, for example, the bonding
pins may take the form of blind rivets wherein the rivet head is
barbed or otherwise enhanced to provide contact and pierce
insulators on the opposed mounting surface.
FIG. 5 illustrates another rail assembly configuration for
promoting electrical bonding in a mounting system, under an
embodiment of the invention. As described, an embodiment of FIG. 5
provides for use of sharp internal bonding features 510, instead
of, for example, the discrete bonding pins 410 (FIG. 4) or the
strip 310 (FIG. 3). For simplicity, the rail assembly 500 is shown
to have a construction described with other embodiments provided
for herein.
In one embodiment, the sharp internal bonding feature 510 may be
provided to be integral to the cross-section of the bottom rail
section 506, regardless of whether the rails have been extruded,
rolled, or formed by other means. Such bonding features 510 may be
designed to penetrate into the solar module frame 504 when the
mounting system is compressed. The bonding features 510 may be made
continuous, as through an extrusion or rolling process. As an
alternative or addition, the bonding features are enhanced by a
secondary machining or grinding process that removes material to
yield intermediate gaps 502 and thereby create the discrete bonding
features 510 illustrated in FIG. 5. The benefit of utilizing
discrete bonding features 510 over a continuous bonding feature is
that the discrete bonding features reduce line contact features to
point contacts. This localizes stresses that are capable of
piercing insulating layers on the mating surface. Although the
bonding features are illustrated as placed on the bottom rail
section 506, they could alternately or additionally be placed on
the solar module frame 504 and/or top rail section 505.
One or more embodiments provide that alternative forms of rail
enhancement are used to provide integrated bonding features. In one
implementation, the surfaces of the top and bottom rail sections
105, 106 (FIG. 1A) may be pierced using dies to create a sharp
protrusion on, for example, the ledge surface 124 (FIG. 1A). Under
one implementation, die work is performed on the ledge surface 124
to create sharp louvers analogous to the features 205 of bonding
clip 210 (see FIG. 2A). In another implementation, a drilling
procedure may lift material out of the hole to create a sharp
raised collar, such as can be achieved through thermal drilling and
other collaring equipment.
FIG. 6 is an exploded view of a mounting assembly that includes a
strut runner, under an embodiment of the invention. A lower rail
section 606 of a rail assembly (not shown) may include a base
surface 608 that secures to a strut runner 610. The bolt 630 may
extend through an opening 609 of the base surface 608, so as to be
received by structures that engage the strut runner 610.
The lower rail section 606 (and this rail assembly) may extend in
an orthogonal direction as compared to the direction of the strut
runner 610. The strut runner 610 may include a slot 612 that
receives an attachment bolt 630, extending from the bottom rail
section 606. In one implementation, the attachment bolt 630 is
separate from a compression bolt or mechanism used with the rail
assembly. The bolt 630 may be received by a washer mechanism 620,
which engages slot 612, to enable the bottom rail section 606 to
secure to the strut runner 610. The slot 612 may also hold a strut
nut 622 for receiving and retaining the bolt 630. The bottom rail
section 606 is then secured to the strut runner 610 through a
tightening of the bolt 630 and strut nut 622.
The strut runner 610 may secure to the underlying structure so as
to retain the rail assembly in place. Multiple strut runners may be
used in one mounting assembly to hold multiple rail assemblies in
position. The resulting assembly may retain solar modules in series
and/or in parallel, and/or in column and row-wise alignment.
Electrical bonding may be enhanced between the bottom rail section
606 and strut runner 610 through the use of washer mechanism 620.
The washer mechanism 620 may incorporate a hole 619 for passage of
the bolt 630. The washer mechanism 620 may additionally contain
sharp protrusions 624 designed to promote electrical contact
between the strut runner 610 and bottom rail section 606 when
compression is present from bolt 630 and strut nut 622. As such,
protrusions 624 may be provided on both the top and bottom surface
of the washer mechanism 620 (bottom surface not shown).
Alternately, proper electrical bonding between the bottom rail
section 606 and strut runner 610 may be achieved without the
bonding washer mechanism 620. As an alternate method, the washer
633 may take the form of a serrated or toothed washer capable of
bonding the bottom rail section 606 to bolt 630. The bolt 630 may
maintain electrical contact to strut nut 622 through the threaded
interface, and the strut nut 622 may be bonded to the strut runner
610 through protrusions that engage the strut runner 610 during
compression.
While a strut runner 610 has been used to describe the structural
and electrical attachment of the bottom rail section 606, alternate
implementations and designs may use other members that are capable
of achieving the same or similar effect. As examples, structural
channel, beams, bar, or other members may be used with appropriate
fasteners. As such, the strut runner 610 should simply be viewed as
an illustrative embodiment for securing a rail assembly or a
section thereof.
FIG. 7 illustrates a mounting assembly 700 comprising a set of
strut runners 712, 722 and a set of mounting rails, under an
embodiment of the invention. In FIG. 7, rail assemblies are assumed
to have a construction such as described with, for example, an
embodiment of FIG. 1A. Mounting rail assemblies 710, 720, and 730
include both top and bottom rail sections. The mounting assembly
700 holds multiple solar panels 742,744,746,748. As mentioned
elsewhere, the solar panels may individually comprise only one
element of a solar module that has both panel and frame. For
simplicity, only the panels of the solar modules are shown in FIG.
7.
With regards to FIGS. 1 and 7, to properly retain the frames that
directly support the solar panels 742,744,746,748, the mounting
rail assemblies 710, 720, 730 may be secured at fixed distances
from each other to provide for the width of the solar panels
742,744,746,748 and their associated frames 104 (FIG. 1A), such
that they may be compressed and retained on a common edge. Strut
runners 712, 722 provide such a fixed spacing within the mounting
system when the lower rail sections are secured to the strut
runners, as illustrated by FIG. 6. Numerous variations are possible
to the mounting assembly 700. For example, although the strut
runners 712, 722 are shown as continuous members, they may be
deployed as shorter discrete sections secured to an underlying
surface such as a roof.
In addition to achieving a fixed spacing and physical arrangement
of the rail assemblies 710, 720, 730 the strut runners 712, 722 may
also provide electrical bonding between adjacent rail assemblies
within the mounting system. Assuming the strut runners are
fabricated from a metal or other electrically conductive material
then the electrical bond between each rail set 710, 720, 730 and
the corresponding strut runner 712, 722 is communicated to the
other rail assemblies utilizing the strut runner as the common
conductor or buss bar. Thus, for example, the set provided by
panels 742 and 748 may be connected as columns, as well as the set
provided by panels 744 and 746. As provided with numerous
embodiments described herein, conductive elements 102 (FIG. 1A) may
conduct electrical current from the frame (not shown in FIG. 7) of
the solar module to the attached rail assembly 710, 720, 730.
Directional arrow 752 illustrates such a conductive path, which can
occur at discrete locations on the mounting assembly 700,
coinciding with placement of conductive elements, as described with
any of the embodiments provided for herein. Under an embodiment
such as described with FIG. 6, the conductive path between one of
the rail assemblies 720, 720, 730 is further extended to the
connected strut runner 712, 722. Directional arrow 754 illustrates
such a conductive path, which enables the rail assemblies to use
the strut runners 712, 722 as buss bars. The strut runners 712, 722
may ground or direct the current away from the mounting assembly,
as illustrated by the directional arrow 756. As such, conductive
paths may be defined by the directional arrows 752, 754 and/or
756.
As an alternative or addition, one or more embodiments provide the
solar module assembly as a whole may be discontinuous, or assembled
in discrete sections. Furthermore, the strut runners and the rail
assemblies may be electrically discontinuous. In such cases,
electrical continuity for bonding may be achieved by, for example,
extending a wire or other conductor between discrete strut runners
or between discrete sections of the assembly as a whole.
Alternatively, the same effect may be achieved if solar modules at
each discrete section are bonded to each rail assembly on each of
their respective edge section. The bonding between one solar module
and both rail assemblies of that solar module may provide the
electrical continuity that may otherwise be absent amongst the
discrete sections.
Because of the ability of the rail assemblies 710, 720, 730 and
strut runners 712, 722 to serve as electrical buss bars, a common
bonding point 760 may be used to bond (or ground) the entire
mounting system 700, inclusive of strut runners, mounting rail
sets, ancillary hardware, and solar modules through a conductor 770
to a designated point such as a grounding rod or other location.
Thus, for example, conductive paths illustrated by the directional
arrows 752 (frame to rail assembly), 754 (rail assembly to strut
runner) and 756 (along strut runner) may carry to the conductor 770
via the point 760. As such, bonding point 760 may be used to
commonly bond all elements within a solar array including the
mounting system and solar modules.
To further illustrate how a single bonding point 760 may be used to
commonly bond the entire solar array, the current paths may be
traced through the system with reference to FIG. 1A and FIG. 7.
Beginning at bonding point 760 which bonds conductor 770 to strut
runner 712, the bottom rail section 106 (FIG. 1A) of each rail
assembly 710, 720, 730 may be bonded to strut runner 712. An
embodiment such as described with FIG. 6 may be used to bond the
strut runner 712 to the rail assemblies. Each of the bottom rail
sections 106 may be bonded to the corresponding top rail sections
105 through compression bolts 130 and receiving structures 132.
Furthermore, each solar module 101 may be bonded to one or more
rail assemblies through any of the embodiments described above. The
solar module frame 104 (FIG. 1A) may be electrically bonded to a
single rail assembly when it is in physical contact with two since
one or more of the underlying strut runners 712, 722 are capable of
bonding adjacent rail assemblies. Thus, for example, solar modules
placed in column alignment (as shown by panels 742 and 748) may be
bonded together by the rail assemblies, while solar modules aligned
in rows (as shown by panels 742 and 744) may be bonded by the strut
runners 712, 722. Because of the multiple and redundant bonding
points and therefore current paths provided within the mounting
system and afforded by the capacity of rail assemblies and strut
runners to act as buss bars, a single bonding point 760 is
sufficient to bond all elements within the assembly 700. If desired
and for sake of redundancy, a second bonding point (in addition to
bonding point 760) may be established on strut runner 712, or any
conductive element within the array.
Although the descriptions above contain many specifics, these
should not be construed as limiting the scope of the invention but
as merely providing illustrations of some embodiments.
* * * * *
References